package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        //封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }
   //缓存穿透解决方法，返回空值
    public <R, ID> R queryWitPassThrough(String keyPrefix, ID id, Class<R> type,
                                         Function<ID, R> dbFallback
            , Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        //从redis中查询商铺缓存
        if (StringUtils.isNotBlank(json)) {
            return JSONUtil.toBean(json, type);
        }
        if (json != null) {
            return null;
        }
        //不存在，查询数据库
        R r = dbFallback.apply(id); // 使用Function接口查询数据库
        if (r == null) { // 如果数据库中也不存在
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //存在，写入redis并返回
        this.set(key, r, time, unit);
        return r;

    }
   // 逻辑过期解决缓存击穿
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public <R, ID> R queryWithLogicalExpire(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        //从redis中查询商铺缓存
        if (StringUtils.isBlank(json)) {
            //返回空
            return null;
        }
        //josn转对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        //判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //未过期，直接返回
            return r;
        }
        //已过期，需要缓存重建
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        if (isLock) {
            //开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //查询数据库
                    R r1 = dbFallback.apply(id);
                    //写入redis
                    this.setWithLogicalExpire(key, r1, time, unit);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }
        return r;

    }



    public boolean tryLock(String key){
        Boolean flag=stringRedisTemplate.opsForValue().setIfAbsent(key,"1",10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    public void unLock(String key){
        stringRedisTemplate.delete(key);}
}
